Projector

ABSTRACT

A projector includes a projection lens, a projector body, and an angle adjustment unit. In the projection lens, a U-shaped optical path is formed of optical axes CL 1  to CL 3 . A lens barrel is a U-shaped barrel. The angle adjustment unit includes a fitting portion, a mounting flange, a fixing unit, a mount ring, and bearings. The projection lens is supported so as to be rotationally movable around the optical axis CL 1 . The fixing unit includes a mounting hole, a fixing screw, and a screw hole. The mounting hole is formed in the shape of an arc. The fixing screw is screwed with the screw hole through the mounting hole, so that the lens barrel is fixed to a housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of PCT International Application No.PCT/JP2017/010927 filed on 17 Mar. 2017, which claims priority under 35U.S.C § 119(a) to Japanese Patent Application No. 2016-068890 filed on30 Mar. 2016. The above application is hereby expressly incorporated byreference, in its entirety, into the present application.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a projector.

2. Description of the Related Art

In recent years, a projector on which an image forming panel, such as aliquid crystal display or a digital micromirror device (DMD), is mountedhas been widespread and the performance of the projector has beenimproved.

JP2002-268033A discloses a liquid crystal projector that irradiates atransmission-type liquid crystal panel with light emitted from a lightsource and enlarges and projects an image, which is displayed on theliquid crystal panel, onto a screen through a projection lens. Further,the liquid crystal projector disclosed in JP2002-268033A includes: adichroic mirror that separates light emitted from the light source intolight having an R component, light having a G component, and lighthaving a B component; liquid crystal panels that are irradiated with thelight having an R component, the light having a G component, and thelight having a B component that are separated by the dichroic mirror,respectively; and a prism that combines an R-image, a G-image, and aB-image formed by being transmitted through the respective liquidcrystal panels.

The liquid crystal projector disclosed in JP2002-268033A is adapted sothat a case holding the projection lens, the transmission-type liquidcrystal panel, and the prism is rotationally movable relative to a lamphousing for housing the light source. Accordingly, an image can beprojected onto the screen while the inclination angle of the opticalaxis of the projection lens with respect to the light source is changed.

SUMMARY OF THE INVENTION

In a case in which an image is projected onto the screen by theprojector, it is necessary to adjust a projection position where animage is to be projected onto a screen, particularly, a position in anup-down direction to allow a user to easily observe the image projectedonto the screen. However, in a case in which the projection positionwhere an image is to be projected onto the screen is to be adjusted inthe liquid crystal projector disclosed in JP2002-268033A, the projectionposition is adjusted while the inclination angle of the optical axis ofthe projection lens is changed. That is, since changing the inclinationangle of the optical axis of the projection lens means that a distancebetween the projection lens and the screen is changed in the directionof the optical axis of the projection lens, the focus of the projectionlens also should be changed whenever the inclination angle of theoptical axis of the projection lens is changed.

The invention has been made in consideration of the above-mentionedcircumstances, and an object of the invention is to provide a projectorthat allows a user to easily perform work for adjusting a projectionposition where an image is to be projected onto a screen.

In order to achieve the object, a projector of the invention includes animage forming panel, a light source, a housing, a projection lens, andan angle adjustment unit that adjusts a mounting angle of the projectionlens mounted on the housing around a first optical axis. The imageforming panel displays an image. The light source illuminates the imageforming panel. The housing houses the image forming panel and the lightsource. The projection lens includes a first optical system, a firstreflective member, a second reflective member, a second optical system,and a lens barrel. The first optical system focuses illumination lightemitted from the image forming panel illuminated by the light source.The first reflective member is disposed so as to be inclined withrespect to a first optical axis of the first optical system and deflectsthe first optical axis to form a second optical axis. The secondreflective member is disposed so as to be inclined with respect to thesecond optical axis and deflects the second optical axis to form a thirdoptical axis parallel to the first optical axis in a plane including thefirst optical axis and the second optical axis. The second opticalsystem projects illumination light, which is deflected to the thirdoptical axis by the second reflective member, onto a projection surface.The lens barrel holds the first optical system, the first reflectivemember, the second reflective member, and the second optical system andis mounted on a barrel-mounting surface of the housing. The angleadjustment unit adjusts a mounting angle of the projection lens mountedon the housing around the first optical axis.

It is preferable that the lens barrel is a U-shaped barrel including afirst holding member holding the first optical system, a second holdingmember holding the second optical system, and a joint portion joiningthe first holding member to the second holding member, and relationshipsof “H1<R1” and “W<R1” are satisfied in a case in which a distancebetween the first optical axis and an upper end of the housing in anup-down direction of the housing orthogonal to the first optical axis isdenoted by H1, a distance between the first optical axis and one sidesurface of the housing in a lateral direction of the housing orthogonalto the first optical axis and the up-down direction is denoted by W, anda distance between the first optical axis and a portion of the secondholding member, which is closest to the first optical axis, is denotedby R1 in an interference region where the second holding member housingthe second optical system protrudes toward the housing from thebarrel-mounting surface.

It is preferable that the housing includes a corner where the upper endand the one side surface cross each other and a relationship of “L<R1”is satisfied in a case in which a distance between the first opticalaxis and the corner is denoted by L.

It is preferable that relationships of “R2<H1” and “R2<H2” are satisfiedin a case in which a distance between the first optical axis and a lowerend of the housing in the up-down direction is denoted by H2 and adistance between the third optical axis and a maximum outer diameter ofthe second holding member in a radial direction is denoted by R2.

It is preferable that the angle adjustment unit adjusts the angle atleast between a first mounting angle where the first optical axis andthe third optical axis coincide with each other in the lateral directionand a second mounting angle where the first optical axis and the thirdoptical axis coincide with each other in the up-down direction.

It is preferable that the angle adjustment unit supports the lens barrelso that the lens barrel is rotationally movable relative to the housing.

It is preferable that the angle adjustment unit includes a long holethat is provided in one of the lens barrel and the housing, and a fixingscrew that is screwed with the other of the lens barrel and the housingthrough the long hole.

It is preferable that the angle adjustment unit includes a long hole anda fixing screw and supports the lens barrel so that the lens barrel isrotationally movable relative to the housing, and one end of the longhole is in contact with the fixing screw in a state in which theprojection lens is positioned at the first mounting angle and the otherend of the long hole is in contact with the fixing screw in a state inwhich the projection lens is positioned at the second mounting angle.

It is preferable that the angle adjustment unit includes a plurality ofmounting holes provided in one of the lens barrel and the housing aroundthe first optical axis and a fixing screw screwed with the other of thelens barrel and the housing through any one of the plurality of mountingholes.

It is preferable that the angle adjustment unit includes a plurality ofmounting holes and a fixing screw and supports the lens barrel so thatthe lens barrel is rotationally movable relative to the housing, and theplurality of mounting holes include a first mounting hole with which thefixing screw is screwed in a state in which the projection lens ispositioned at the first mounting angle, a second mounting hole withwhich the fixing screw is screwed in a state in which the projectionlens is positioned at the second mounting angle, and third mountingholes which are arranged between the first mounting hole and the secondmounting hole at equal angular intervals.

According to the invention, it is possible to easily adjust a projectionposition where an image is to be projected onto a screen, and to easilyperform work for adjusting the projection position without needing tochange a focus after the adjustment of a projection position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a projector of the invention.

FIG. 2 is a longitudinal sectional view of the projector.

FIG. 3 is a perspective view showing the structure of a fixing unit.

FIG. 4 is a cross-sectional view of main portions taken along line IV-IVof FIG. 2.

FIG. 5 is a cross-sectional view of main portions showing a state inwhich a projection lens is rotated clockwise by an angle of 90° from astate shown in FIG. 4.

FIG. 6 is a back view showing a positional relationship between a caseand the projection lens at a first mounting angle.

FIG. 7 is a back view showing a positional relationship between the caseand the projection lens at a second mounting angle.

FIG. 8 is a side view showing a positional relationship between the caseand the projection lens at the first mounting angle.

FIG. 9 is a diagram illustrating the adjustment of a projection positionwhere an image is to be projected onto a screen that is performed usinga change in the mounting angle of the projection lens.

FIG. 10 is a perspective view showing the structure of an angleadjustment unit of a second embodiment.

FIG. 11 is a cross-sectional view of main portions around a fixing unitof the second embodiment.

FIG. 12 is a perspective view showing the structure of an angleadjustment unit of a third embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

As shown in FIG. 1, a projector 2 of this embodiment includes aprojection lens 10, a projector body 60, and an angle adjustment unit61.

As shown in FIG. 2, the projection lens 10 includes a first opticalsystem 11, a second optical system 12, a first mirror 13 serving as afirst reflective member, a second mirror 14 serving as a secondreflective member, a first holding member 15, a second holding member16, and a joint portion 17. The first holding member 15, the secondholding member 16, and the joint portion 17 form a lens barrel 18.

The first optical system 11 includes a first lens 21 and a second lens22. Each of these first and second lenses 21 and 22 is shown as a singlelens for simplification in FIG. 2, but is actually formed of a pluralityof lens groups. The first optical system 11 focuses illumination lightemitted from an image forming panel 67. In this embodiment, the firstoptical system 11 forms an image, which is formed on the image formingpanel 67, on an imaging plane 23 as an intermediate image.

The first mirror 13 is disposed between the first optical system 11 andthe imaging plane 23 of the intermediate image that is formed by thefirst optical system 11. The first mirror 13 deflects an optical axisCL1 of the first optical system 11 by reflection to form an optical axisCL2. In this embodiment, the first mirror 13 deflects the optical axisCL1 by an angle of 90° to form the optical axis CL2.

The first holding member 15 integrally holds the first optical system 11and the first mirror 13. The first holding member 15 includes a firstbody part 24, a mounting tube 25, a first lens frame 26, and a secondlens frame 27. The first body part 24 is formed of a square tube havinga substantially rectangular parallelepiped shape. One corner of a lowerplate 24 a of the first body part 24 is cut obliquely, so that aninclined surface portion 24 b is formed. The first mirror 13 is fixed tothe inner surface of the inclined surface portion 24 b.

A first mounting hole 24 d of the first optical system 11 is formed inan inlet-side front plate 24 c that faces the inclined surface portion24 b. The mounting tube 25, the first lens frame 26, and the second lensframe 27 are mounted on the first mounting hole 24 d by mounting screws28 and 29. Further, the mounting tube 25, the first lens frame 26, andthe second lens frame 27 may be fixed to the first mounting hole 24 d byusing an adhesive instead of or in addition to the mounting screws 28and 29 and the like. A second mounting hole 24 f is formed in an upperplate 24 e of the first body part 24 of the first holding member 15.

The mounting tube 25 includes a fitting portion 74 and a mounting flange75 of the angle adjustment unit 61 to be described later.

The second optical system 12 includes a third lens 35, a fourth lens 36,a fifth lens 37, and a sixth lens 38. Each of the fourth to sixth lenses36 to 38 is shown as a single lens for simplification in FIG. 2, but isactually farmed of a plurality of lens groups. The second optical system12 enlarges the intermediate image, which is formed on the imaging plane23 by the first optical system 11, and projects the enlargedintermediate image onto, for example, a screen 39 that is a projectiontarget. The first optical system 11 and the second optical system 12 aredescribed in detail in “an optical system for projection and aprojection-type display device” of, for example, JP2015-035085,JP2015-045989, and the like, and optical systems described in these canbe used as the first optical system 11 and the second optical system 12.According to the optical system for projection and the projection-typedisplay device, an optical system of which various aberrations aresatisfactorily corrected at a wide angle and which has high projectionperformance is obtained.

The second mirror 14 is disposed between the third and fourth lenses 35and 36 of the second optical system 12. The second mirror 14 deflectsthe optical axis CL2 by reflection to form an optical axis CL3. In thisembodiment, the second mirror 14 deflects the optical axis CL2 by anangle of 90° to form the optical axis CL3.

In this embodiment, as described above, an incidence-side optical axisCL1 of the first optical system 11 is reflected by the first mirror 13,is deflected at an angle of 90°, and becomes an emission-side opticalaxis CL2. Further, an incidence-side optical axis CL2 of the secondoptical system 12 is reflected by the second mirror 14, is deflected atan angle of 90°, and becomes an emission-side optical axis CL3. That is,the optical axis CL3 is parallel to the optical axis CL1 in a planeincluding the optical axes CL1 and CL2. The optical axes CL1 to CL3correspond to first to third optical axes of the invention.

The second holding member 16 integrally holds the second optical system12 and the second mirror 14. The second holding member 16 includes asecond body part 40, a mounting plate 41, a third lens frame 42, afourth lens frame 43, and a fifth lens frame 44. The second body part 40is formed of a square tube having a substantially rectangularparallelepiped shape. One corner of an upper plate 40 a of the secondbody part 40 is cut obliquely, so that an inclined surface portion 40 bis formed. The second mirror 14 is fixed to the inner surface of theinclined surface portion 40 b.

A third mounting hole 40 d is formed in a lower plate 40 c that facesthe inclined surface portion 40 b in a vertical direction. Anemission-side end face of the third lens frame 42 is inserted into thethird mounting hole 40 d from below in the vertical direction. A flange42 a is formed at the emission-side end face of the third lens frame 42.The flange 42 a and the lower plate 40 c are fixed to each other bymounting screws 46.

A flange 40 e extends from a front end face that faces the inclinedsurface portion 40 b in a horizontal direction. The mounting plate 41 isfixed to the flange 40 e by mounting screws 47. The mounting plate 41includes a mounting hole 41 a. The fifth lens frame 44, which holds thesixth lens 38, is inserted into the mounting hole 41 a. The fifth lensframe 44 is fixed to the mounting plate 41 by mounting screws 48. Thefourth lens frame 43 is fitted around the incidence-side end portion ofthe fifth lens frame 44.

Further, a flange 42 b is formed at the incidence-side end face of thethird lens frame 42. Mounting holes 57 to be described later are formedin the flange 42 b.

As shown in FIG. 2, the joint portion 17 includes screw holes 56,mounting holes 57, and mounting screws 58. One of the first and secondholding members 15 and 16 is provided with the screw holes 56. In thisembodiment, the upper plate 24 e of the first holding member 15 isprovided with the screw holes 56. The other of the first and secondholding members 15 and 16 is provided with the mounting holes 57. Inthis embodiment, the flange 42 b of the second holding member 16 isprovided with the mounting holes 57. The mounting screws 58 are insertedinto the mounting holes 57 and are fastened to the screw holes 56 to fixthe first holding member 15 to the second holding member 16.

The first and second holding members 15 and 16 are individuallyassembled. The first and second holding members 15 and 16 are joined toeach other through the joint portion 17 in a state in which theemission-side optical axis CL2 of the first optical system 11 and theincidence-side optical axis CL2 of the second optical system 12 arealigned with each other. As a result, the lens barrel 18 is assembled.In the lens barrel 18 that is assembled in this way, a U-shaped opticalpath is formed by the optical axis CL2, the incidence-side optical axisCL1 of the first optical system 11, and the emission-side optical axisCL3 of the second optical system 12. For this reason, the lens barrel18, which holds the first optical system 11, the second optical system12, the first mirror 13, and the second mirror 14, is a U-shaped barrel.

The projection lens 10 is mounted on the projector body 60 through theangle adjustment unit 61. The projector body 60 is adapted so that alight source 66, the image forming panel 67, and a control unit 68 arehoused in a housing 65 having a substantially rectangular parallelepipedshape.

A transmission-type liquid crystal panel is used as the image formingpanel 67. The light source 66 is disposed on the back side of the imageforming panel 67, that is, the side of the image forming panel 67opposite to the projection lens 10. A light emitting diode (LED), whichsimultaneously emits light having three colors of RGB, is used as thelight source 66, and the light source 66 illuminates the image formingpanel 67. A xenon lamp, a halogen lamp, and a super high-pressuremercury lamp, which emit white light, may be used instead of the LED.The projection lens 10 projects illumination light, which is emittedfrom the image forming panel 67 illuminated by the light source 66, ontoa projection surface, for example, the screen 39.

The control unit 68 turns on the light source 66 and allows images,which have three colors of RGB, to be displayed on an image formingsurface 67 a. The control unit 68 performs the following processing aswell. In a case in which, for example, the projection lens 10 includesan electrical control function and the control unit 68 receives anoperation signal of a zoom dial 71, the control unit 68 adjusts the sizeof the image to be projected onto the screen 39. In a case in which thecontrol unit 68 receives an operation signal of a focus dial 73, thecontrol unit 68 operates a focus adjustment mechanism (not shown) of theprojection lens 10 to adjust the focus of the image projected onto thescreen 39.

As shown in FIG. 2, an image is projected onto the screen 39 above theemission-side optical axis CL3 of the second optical system 12. Thecenter of the image forming panel 67 is fixed so as to be shifted in adirection opposite to a direction in which the central position of theprojected image (the projection surface of the screen 39) is shiftedfrom the incidence-side optical axis CL1 of the first optical system 11,that is, to the lower side in the direction of the emission-side opticalaxis CL2 of the first optical system 11.

The angle adjustment unit 61 includes a fitting portion 74, a mountingflange 75, a fixing unit 76 (see FIG. 3), a mount ring 77, bearings 78and 79, and a mount holding portion 80. The mount holding portion 80 isformed in a cylindrical shape, and is formed integrally with the housing65. The mount holding portion 80 holds the mount ring 77 and thebearings 78 and 79.

The fitting portion 74 is provided at the incidence-side end portion ofthe mounting tube 25, and the mounting flange 75 is provided on theemission side of the fitting portion 74. The fitting portion 74 isformed in a columnar shape so that the outer peripheral surface of thefitting portion 74 is fitted to the inner peripheral surfaces of thebearings 78 and 79.

The bearings 78 and 79 are radial bearings, and are disposed between themount holding portion 80 and the fitting portion 74. The first opticalsystem 11 is held so that the position of the optical axis CL1 isaligned with the central axes of the bearings 78 and 79. Accordingly,the projection lens 10 is supported so as to be rotationally movablearound the optical axis CL1.

The mount ring 77 is formed in the shape of a ring that has an innerdiameter corresponding to the outer diameter of the mounting tube 25.The mount ring 77 is fitted to the mount holding portion 80 and coversand hides the bearings 78 and 79.

As shown in FIG. 3, the mount ring 77 includes a mounting surface 77 a(barrel-mounting surface). The mounting surface 77 a is a flat surfacethat is orthogonal to the central axes of the bearings 78 and 79, andfaces a mounting surface 75 a of the mounting flange 75 in a state inwhich the fitting portion 74 is fitted to the bearings 78 and 79.

The fixing unit 76 includes a mounting hole 81, a fixing screw 82, and ascrew hole 83. The mounting hole 81 is formed in one of the mountingflange 75 and the mount ring 77. In this embodiment, the mounting hole81 is formed in the mounting flange 75. The mounting hole 81 is anarc-shaped long hole that passes through the mounting flange 75 and hasa center on the optical axis CL1. Further, in this embodiment, themounting hole 81 is formed in the shape of an arc having a central angleθ1 (see FIG. 4) of 90°. The screw hole 83 is formed in the other of themounting flange 75 and the mount ring 77. In this embodiment, the screwhole 83 is formed in the mount ring 77.

The screw hole 83 is formed on the mounting surface 77 a. The screw hole83 is disposed so as to be positioned in the mounting hole 81, and isscrewed with the fixing screw 82 inserted into the mounting hole 81.Accordingly, the mounting surfaces 75 a and 77 a are in close contactwith each other and the mounting flange 75 is fastened to the mount ring77 with the screw. That is, the lens barrel 18 is fixed to the housing65 by the fixing unit 76.

Since the mounting hole 81 is an arc-shaped long hole as describedabove, the projection lens 10 can be mounted while the mounting angle ofthe projection lens 10 mounted on the housing 65 is adjusted around theoptical axis CL1. That is, the projection lens 10 is moved rotationallyaround the optical axis CL1 from a position where the fixing screw 82 isin contact with one end 81A of the mounting hole 81 as shown in FIG. 4and is screwed with the screw hole 83, and the mounting angle of theprojection lens 10 can be adjusted to a position where the fixing screw82 is in contact with the other end 81B of the mounting hole 81 as shownin FIG. 5 and is screwed with the screw hole 83.

Since the mounting hole 81 has a central angle θ1 of 90° in thisembodiment, the angle adjustment unit 61 can adjust the mounting angleof the projection lens 10 in an angular range of 90° around the opticalaxis CL1. Specifically, the angle adjustment unit 61 can adjust themounting angle between a first mounting angle shown in FIG. 6 and asecond mounting angle shown in FIG. 7. One end 81A of the mounting hole81 is in contact with the fixing screw 82 at the first mounting angle,and the other end 81B of the mounting hole 81 is in contact with thefixing screw 82 at the second mounting angle.

In the following description, the optical axis CL1 corresponds to anX-axis direction, an up-down direction of the housing 65 orthogonal tothe X-axis direction is referred to as a Z-axis direction, and a lateraldirection of the housing 65 orthogonal to the X-axis direction and theZ-axis direction is referred to as a Y-axis direction.

As shown in FIG. 6, the optical axis CL1 and the optical axis CL3 of theprojection lens 10 coincide with each other in the Y-axis direction atthe first mounting angle. Further, as shown in FIG. 7, the optical axisCL1 and the optical axis CL3 coincide with each other in the Z-axisdirection at the second mounting angle where the projection lens 10 isrotated clockwise by an angle of 90° from the first mounting angle.

Since the lens barrel 18 is a U-shaped barrel as described above, thelens barrel 18 includes a portion where the second optical system 12 andthe second holding member 16 protrude toward the housing 65 from themounting surface 77 a. The portion where the second optical system 12and the second holding member 16 protrude toward the housing 65 from themounting surface 77 a in the X-axis direction as shown in FIG. 8 isreferred to as an interference region E.

In a case in which a distance between the optical axis CL1 and an upperend 65A of the housing 65 in the Z-axis direction is denoted by H1, adistance between the optical axis CL1 and one side surface 65B of thehousing 65 in the Y-axis direction is denoted by W, and a distancebetween the optical axis CL1 and a portion of the second holding member16, which is closest to the optical axis CL1, is denoted by R1 in theinterference region E, the projection lens 10 has relationships of“H1<R1” and “W<R1”. Accordingly, since there is a margin in the positionof the lens barrel 18 with respect to the upper end 65A and the sidesurface 65B of the housing 65, the lens barrel 18 is not in contact withthe housing 65 and the mounting angle can be smoothly adjusted.

Further, the housing 65 includes a corner 65C where the upper end 65Aand the side surface 65B cross each other. In a case in which a distancebetween the optical axis CL1 and the corner 65C is denoted by L, theprojection lens 10 has a relationship of “L<R1”. Accordingly, sincethere is a margin in the position of the lens barrel with respect to thecorner 65C, the lens barrel 18 comes into contact with the corner 65Cand the mounting angle can be smoothly adjusted in a case in which thelens barrel 18 is moved rotationally.

Furthermore, in a case in which a distance between the optical axis CL1and a lower end 65D of the housing 65 in the Z-axis direction is denotedby H2 and a distance between the optical axis CL3 and the maximum outerdiameter of the second holding member 16 in a radial direction isdenoted by R2 in the interference region E, the projection lens 10 hasrelationships of “R2<H1” and “R2<H2”. Accordingly, in a state in whichthe projection lens 10 shown in FIG. 7 is positioned at the secondmounting angle, the projection lens 10 does not protrude from the upperend 65A and the lower end 65D of the housing 65. Since the outerperipheral surface of the fifth lens frame 44 is largest in theinterference region E, the distance R2 is a distance between the opticalaxis CL3 and the outer peripheral surface of the fifth lens frame 44.

In a case in which the projector 2 is used, for example, the projectionlens 10 is mounted at the first mounting angle and the image of theimage forming panel 67 (see FIG. 1) is enlarged and projected onto thescreen 39 by the projection lens 10. Further, in a case in which a userwants to adjust a projection position where an image is to be projectedonto the screen 39 to easily observe the image projected onto the screen39, the user loosens the fixing screw 82 to release the fixing of theprojection lens 10 to the housing 65. Then, the user adjusts themounting angle of the projection lens 10 in the angular range betweenthe first mounting angle and the second mounting angle.

In a state in which the projection lens 10 is moved rotationally aroundthe optical axis CL1 from the first mounting angle by an angle α asshown in FIG. 9, the fixing screw 82 is tightened to fix the projectionlens 10 to the housing 65. In a case in which a difference between theprojection position that is obtained in this state and the projectionposition, which is obtained in a case in which the projection lens 10 ispositioned at the first mounting angle and an image is projected, isdenoted by P and a distance between the optical axis CL1 and the opticalaxis CL3 is denoted by D, the projection position can be shifted in theZ-axis direction in the projector 2 by “P=D(1−cos α)”

Since the mounting angle of the projection lens 10 mounted on thehousing 65 around the optical axis CL1 can be adjusted in the projector2 of this embodiment, the projection position where an image is to beprojected onto the screen 39 can be easily adjusted. Further, since itis not necessary to adjust the projection position while changing theinclination angle of the optical axis of the projection lens withrespect to the screen unlike in the projector in the related art, thefocus of the projection lens 10 does not need to be adjusted in a casein which the projection position is to be adjusted.

Second Embodiment

In the first embodiment, an arc-shaped long hole is formed as themounting hole 81 of the fixing unit 76 to allow the mounting angle ofthe projection lens 10 to be adjusted. In contrast, in a secondembodiment shown in FIG. 10, a fixing unit 85 includes a plurality ofmounting holes 86A to 86E, a fixing screw 82, and a screw hole 83. Thesame components as those of the first embodiment will be denoted by thesame reference numerals as those of the first embodiment, and therepeated description thereof will be omitted.

In this embodiment, the five mounting holes 86A to 86E are arrangedaround the optical axis CL1. The fixing screw 82 can be screwed with thescrew hole 83 through the mounting hole 86A (first mounting hole) in astate in which the projection lens 10 is positioned at a first mountingangle. On the other hand, the fixing screw 82 can be screwed with thescrew hole 83 through the mounting hole 86E (second mounting hole) in astate in which the projection lens 10 is positioned at a second mountingangle. As in the first embodiment, the first mounting angle is amounting angle where the optical axis CL1 and the optical axis CL3coincide with each other in the Y-axis direction, and the secondmounting angle is a mounting angle where the optical axis CL1 and theoptical axis CL3 coincide with each other in the Z-axis direction. Forthis reason, an angular interval of 90° around the optical axis CL1 isprovided between the mounting hole 86A and the mounting hole 86E.

As shown in FIG. 11, the mounting holes 86B to 86D (third mountingholes) are arranged between the mounting holes 86A and 86E at equalangular intervals θ2. Since an angular interval of 90° is providedbetween the mounting holes 86A and 86E as described above, the mountingholes 86A to 86E are arranged at angular intervals θ2 (θ2=22.5°). Thefixing screw 82 is screwed with the screw hole 83 through any one of themounting holes 86A to 86E, so that the projection lens 10 is fixed tothe housing 65.

In a case in which the angle of the projection lens 10 mounted on thehousing 65 around the optical axis CL1 is to be adjusted in thisembodiment, the fixing screw 82, which is screwed with the screw hole 83through any one of the mounting holes 86A to 86E, is loosened to releasethe fixing of the projection lens 10 to the housing 65. The projectionlens 10 is moved rotationally around the optical axis CL1 to adjust themounting angle. Further, the fixing screw 82 is tightened through anyone of the mounting holes 86A to 86E, which is different from themounting hole in a case in which fixing is not yet released, to fix theprojection lens 10 to the housing 65. Accordingly, the mounting anglecan be adjusted to mounting angles of a plurality of stagescorresponding to the positions of the mounting holes 86A to 86E from thefirst mounting angle to the second mounting angle.

Third Embodiment

The fixing unit of the angle adjustment unit 61 includes the mountinghole, the fixing screw, and the screw hole in the first and secondembodiments, but is not limited thereto. In a third embodiment shown inFIG. 12, an angle adjustment unit 90 includes a key protrusion 91 and aplurality of key grooves 92A to 92E. The same components as those of thefirst and second embodiments will be denoted by the same referencenumerals as those of the first and second embodiments, and the repeateddescription thereof will be omitted.

The key protrusion 91 is a columnar protruding portion that is providedon the outer periphery of the fitting portion 74 and extends in parallelto the optical axis CL1. The five key grooves 92A to 92E are grooveswhich are formed on the mount ring 77 and to which the key protrusion 91is fitted. The key protrusion 91 can be fitted to the key groove 92A ina state in which the projection lens 10 is positioned at a firstmounting angle. On the other hand, the key protrusion 91 can be fittedto the key groove 92E in a state in which the projection lens 10 ispositioned at a second mounting angle. As in the first and secondembodiments, the first mounting angle is a mounting angle where theoptical axis CL1 and the optical axis CL3 coincide with each other inthe Y-axis direction, and the second mounting angle is a mounting anglewhere the optical axis CL1 and the optical axis CL3 coincide with eachother in the Z-axis direction. For this reason, an angular interval of90° around the optical axis CL1 is provided between the key groove 92Aand the key groove 92E.

The key grooves 92B to 92D are arranged between the key grooves 92A and92E at equal angular intervals θ2. Since an angular interval of 90° isprovided between the key grooves 92A and 92E as described above, the keygrooves 92A to 92E are arranged at angular intervals θ2 (θ2=22.5°).

In a case in which the angle of the projection lens 10 mounted on thehousing 65 around the optical axis CL1 is to be adjusted in thisembodiment, the fitting portion 74 is fitted to the mount ring 77 andthe key protrusion 91 is fitted to any one of the key grooves 92A to92E. Accordingly, the mounting angle can be adjusted to mounting anglesof a plurality of stages corresponding to the positions of the keygrooves 92A to 92E from the first mounting angle to the second mountingangle.

The mounting angle of the projection lens 10 mounted on the housing 65can be adjusted in the angular range of 90° between the first and secondmounting angles in the respective embodiments, but the range of themounting angle is not limited thereto. For example, the mounting anglemay be adapted to be capable of being adjusted in the angular rangelarger than 90° in addition to the first mounting angle and the secondmounting angle.

A transmission-type liquid crystal panel has been used as the imageforming panel 67 in the above-mentioned embodiments, but a reflectiontype liquid crystal panel may be used. In this case, the light source 66is disposed on the front side of the image forming panel 67 andsimultaneously emits irradiation light having three colors of RGB. In acase in which a DMD is used as the image forming panel 67, the lightsource 66 is disposed on the front side of the image forming panel 67and LEDs having three colors of RGB generate light by time sharing insynchronization with timings at which the DMD forms an image havingthree colors.

The first holding member 15 of the lens barrel 18 is formed in the shapeof a square tube in the respective embodiments, but is not limitedthereto. For example, corners of the lower end of the first holdingmember 15 may be formed in a chamfered shape or a curved shape.Accordingly, even though a distance H2 between the optical axis CL1 andthe lower end 65D of the housing 65 in the Z-axis direction is short,the corners of the first holding member 15 does not protrude from thelower end 65D of the housing 65.

A state in which the projector 62 is disposed on a table has beendescribed in the respective embodiments, but the invention may also beapplied to a case in which the projector 62 is used while beingsuspended from the ceiling or the like. Further, an example in which animage is projected onto the screen 39 has been described, but theprojection surface is not limited to the screen 39 and the projector 62can be used as a projector that projects an image onto variousprojection surfaces.

In the respective embodiments, terms, such as orthogonal and parallel,have been used to represent a positional relationship between theplurality of optical axes or the specific numerical values of an angle,such as 90°, have been used for description. However, these terms or thenumerical values include a range to be allowed with an error based onaccuracy required for the optical system.

EXPLANATION OF REFERENCES

-   -   2: projector    -   10: projection lens    -   11: first optical system    -   12: second optical system    -   13: first mirror    -   14: second mirror    -   15: first holding member    -   16: second holding member    -   17: joint portion    -   18: lens barrel    -   21: first lens    -   22: second lens    -   23: imaging plane    -   24: first body part    -   24 a: lower plate    -   24 b: inclined surface portion    -   24 c: front plate    -   24 d: first mounting hole    -   24 e: upper plate    -   24 f: second mounting hole    -   25: mounting tube    -   26: first lens frame    -   27: second lens frame    -   28: mounting screw    -   29: mounting screw    -   35: third lens    -   36: fourth lens    -   37: fifth lens    -   38: sixth lens    -   39: screen    -   40: second body part    -   40 a: upper plate    -   40 b: inclined surface portion    -   40 c: lower plate    -   40 d: third mounting hole    -   40 e: flange    -   41: mounting plate    -   41 a: mounting hole    -   42: third lens frame    -   42 a, 42 b: flange    -   43: fourth lens frame    -   44: fifth lens frame    -   46 to 48: mounting screw    -   56: screw hole    -   57: mounting hole    -   58: mounting screw    -   60: projector body    -   61: angle adjustment unit    -   62: projector    -   65: housing    -   65A: upper end    -   65B: side surface    -   65C: corner    -   65D: lower end    -   66: light source    -   67: image forming panel    -   67 a: image forming surface    -   68: control unit    -   71: zoom dial    -   73: focus dial    -   74: fitting portion    -   75: mounting flange    -   75 a: mounting surface    -   76: fixing unit    -   77: mount ring    -   77 a: mounting surface    -   78, 79: bearing    -   80: mount holding portion    -   81: mounting hole    -   81A: one end    -   81B: the other end    -   82: fixing screw    -   83: screw hole    -   85: fixing unit    -   86A to 86E: mounting hole    -   90: angle adjustment unit    -   91: key protrusion    -   92A to 92E: key groove

What is claimed is:
 1. A projector comprising: an image forming panelthat displays an image; a light source that illuminates the imageforming panel; a housing that houses the image forming panel and thelight source; a projection lens including a first optical system thatfocuses illumination light emitted from the image forming panelilluminated by the light source, a first reflective member that isdisposed so as to be inclined with respect to a first optical axis ofthe first optical system and deflects the first optical axis to form asecond optical axis, a second reflective member that is disposed so asto be inclined with respect to the second optical axis and deflects thesecond optical axis to form a third optical axis parallel to the firstoptical axis in a plane including the first optical axis and the secondoptical axis, a second optical system that projects illumination light,which is deflected to the third optical axis by the second reflectivemember, onto a projection surface, and a lens barrel that holds thefirst optical system, the first reflective member, the second reflectivemember, and the second optical system and is mounted on abarrel-mounting surface of the housing; and an angle adjustment unitthat adjusts a mounting angle of the projection lens mounted on thehousing around the first optical axis.
 2. The projector according toclaim 1, wherein the lens barrel is a U-shaped barrel that includes afirst holding member holding the first optical system, a second holdingmember holding the second optical system, and a joint portion joiningthe first holding member to the second holding member, and relationshipsof “H1<R1” and “W<R1” are satisfied in a case in which a distancebetween the first optical axis and an upper end of the housing in anup-down direction of the housing orthogonal to the first optical axis isdenoted by H1, a distance between the first optical axis and one sidesurface of the housing in a lateral direction of the housing orthogonalto the first optical axis and the up-down direction is denoted by W, anda distance between the first optical axis and a portion of the secondholding member, which is closest to the first optical axis, is denotedby R1 in an interference region where the second holding member housingthe second optical system protrudes toward the housing from thebarrel-mounting surface.
 3. The projector according to claim 2, whereinthe housing includes a corner where the upper end and the one sidesurface cross each other, and a relationship of “L<R1” is satisfied in acase in which a distance between the first optical axis and the corneris denoted by L.
 4. The projector according to claim 2, whereinrelationships of “R2<H1” and “R2<H2” are satisfied in a case in which adistance between the first optical axis and a lower end of the housingin the up-down direction is denoted by H2 and a distance between thethird optical axis and a maximum outer diameter of the second holdingmember in a radial direction is denoted by R2.
 5. The projectoraccording to claim 2, wherein the angle adjustment unit adjusts theangle at least between a first mounting angle where the first opticalaxis and the third optical axis coincide with each other in the lateraldirection and a second mounting angle where the first optical axis andthe third optical axis coincide with each other in the up-downdirection.
 6. The projector according to claim 2, wherein the angleadjustment unit supports the lens barrel so that the lens barrel isrotationally movable relative to the housing.
 7. The projector accordingto claim 6, wherein the angle adjustment unit includes a long hole thatis provided in one of the lens barrel and the housing, and a fixingscrew that is screwed with the other of the lens barrel and the housingthrough the long hole.
 8. The projector according to claim 5, whereinthe angle adjustment unit includes a long hole that is provided in oneof the lens barrel and the housing and a fixing screw that is screwedwith the other of the lens barrel and the housing through the long hole,and supports the lens barrel so that the lens barrel is rotationallymovable relative to the housing, and one end of the long hole is incontact with the fixing screw in a state in which the projection lens ispositioned at the first mounting angle and the other end of the longhole is in contact with the fixing screw in a state in which theprojection lens is positioned at the second mounting angle.
 9. Theprojector according to claim 6, wherein the angle adjustment unitincludes a plurality of mounting holes that are provided in one of thelens barrel and the housing around the first optical axis, and a fixingscrew that is screwed with the other of the lens barrel and the housingthrough any one of the plurality of mounting holes.
 10. The projectoraccording to claim 5, wherein the angle adjustment unit includes aplurality of mounting holes that are provided in one of the lens barreland the housing around the first optical axis and a fixing screw that isscrewed with the other of the lens barrel and the housing through anyone of the plurality of mounting holes, and supports the lens barrel sothat the lens barrel is rotationally movable relative to the housing,and the plurality of mounting holes include a first mounting hole withwhich the fixing screw is screwed in a state in which the projectionlens is positioned at the first mounting angle, a second mounting holewith which the fixing screw is screwed in a state in which theprojection lens is positioned at the second mounting angle, and thirdmounting holes that are arranged between the first mounting hole and thesecond mounting hole at equal angular intervals.